Increased efficiency strainer system

ABSTRACT

In accordance with the present invention, there is provided an increased efficiency strainer system which is particularly suited for use in the emergency core cooling system of a nuclear power plant. In certain embodiments of the present invention, the strainer system includes one or more strainer cassettes or cartridges, with each such cassette or cartridge including a plurality of strainer pockets disposed in side-by-side relation to each other. In these embodiments, multiple cassettes or cartridges may be assembled together to form a strainer module of the strainer system. The strainer pockets of the cartridge each define an inflow end. Within the cartridge, or the module including multiple cartridges, the inflow ends of one or more of the strainer pockets may be enclosed by an elastic metal membrane. When in a closed position, the membrane prevents liquid flow into the corresponding strainer pocket via the inflow end thereof. The membrane remains closed when only a low pressure load is exerted thereon, but is deflected or deformed into an open position when a high pressure load is exerted thereon. The movement of the membrane to its open position effectively opens the corresponding strainer pocket, thus allowing for the flow of liquid into the interior of the strainer pocket via the inflow end thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates generally to strainer devices and, moreparticularly, to a suction strainer of modular construction which isadapted to remove entrained solids or debris from the cooling liquid ina nuclear reactor, and to reduce head loss across the strainer in thepresence of liquids with such entrained solids or debris.

2. Description of the Related Art

A nuclear power plant typically includes an emergency core coolingsystem that circulates large quantities of cooling water to criticalreactor areas in the event of accidents. A boiling water reactor or BWRcommonly draws water from one or more reservoirs, known as suppressionpools, in the event of a loss of coolant accident. More particularly,water is pumped from the suppression pool to the reactor core and thencirculated back to the suppression pool in a closed loop. A loss ofcoolant accident can involve the failure of reactor components thatintroduce large quantities of solid matter into the cooling water, whichentrains the solids and carries them back to the suppression pool. Forexample, if a loss of coolant accident results from the rupture of ahigh pressure pipe, quantities of thermal insulation, concrete, paintchips and other debris can be entrained in the cooling water.

In contrast to a BWR, a pressurized water reactor or PWR, after a lossof coolant accident, typically draws cooling water from a reactor waterstorage tank and, after a signal, shuts off the flow from the storagetank and recirculates this water through the reactor. In this regard,the pressurized water reactor has a containment area that is dry untilit is flooded by the occurrence of an accident, with the emergency corecooling system using a pump connected to a sump in the containment areato circulate the water through the reactor. Nevertheless, the water thatis pumped in the event of an accident will also usually containentrained solids that typically include insulation, paint chips, andparticulates. Thus, in both types of reactors (i.e., boiling waterreactors and pressurized water reactors), cooling water is drawn from areservoir and pumped to the reactor core, with entrained solids ordebris potentially impairing cooling and damaging the emergency corecooling system pumps if permitted to circulate with the water.

In recognition of the potential problems which can occur as a result ofthe presence of entrained solids or debris in the coolant water of theemergency core cooling system, it is known in the prior art to placestrainers in the coolant flow path upstream of the pumps, usually byimmersing them in the cooling water reservoir. It is critical that thesestrainers be able to remove unacceptably large solids without undulyretarding the flow of coolant. In this regard, the pressure (head) lossacross the strainer must be kept to a minimum. Strainers are commonlymounted to pipes that are part of the emergency core cooling system andthat extend into the suppression pool or sump, with the emergency corecooling system pumps drawing water through the strainers and introducingthe water to the reactor core. There has been considerable effortexpended in the prior art in relation to the design of strainers todecrease head loss across the strainer for the desired coolant flow.Existing strainers often include a series of stacked perforated hollowdiscs or flat perforated plates and a central core through which wateris drawn by the emergency core cooling system pump. The perforated discsor plates prevent debris larger than a given size from passing thestrainer perforations and reaching the pumps.

As is apparent from the foregoing, large amounts of fibrous material canenter the circulating coolant water in the event of a reactor accident.This fibrous material, which often originates with reactor pipe orcomponent insulation that is damaged and enters the emergency corecooling system coolant stream in the event of a loss of coolantaccidents indicated above, typically accumulates on the strainersurfaces and captures fine particulate matter in the flow. The resultingfibrous debris bed on the strainer surfaces can quickly block the flowthrough the strainer, even though the trapped particulates may be smallenough to pass through the strainer perforations. More particularly, thedebris accumulates in a fluffy density in and on the strainer until thestrainer becomes completely covered with a fiber and particulate debrisbed. Once this occurs, the strainer loses its complex geometric surfaceadvantages and becomes a simple strainer. Hours to days later, somedebris typically dissolves into solution and interacts with chemicalspresent in the containment. At the same time, containment temperaturesare trending down. This phenomenon causes certain chemical precipitatesto form which eventually make their way to the strainer. Once they reachthe strainer surface, the pressure drop across the strainer typicallydramatically increases.

The prior art has attempted to address the above-described flow blockageeffect by making the strainer larger, the goal being to distribute thetrapped debris over more area, reducing the velocity through the debrisbed, and further reducing the head loss across the strainer as a whole.This solution, however, is often undesirable since the available spacein a reactor for a suction strainer is usually limited, and furtherbecause larger strainers are typically more costly. As a result, thesituation sometimes arises wherein the expected debris load after a lossof coolant accident can dictate a need for strainers that are too largefor the space allotted for them in the containment area. Moreover, largestrainers are often more difficult work with and thus more costly toinstall. In addition, prior art emergency core cooling system strainershave been constructed in ways that make them somewhat expensive tofabricate.

The present invention addresses the aforementioned needs and overcomesmany of the deficiencies associated with existing nuclear power plantstrainer designs providing a strainer design which is specificallysuited to reduce the differential pressure experienced across thestrainer in nuclear power plants with medium to high fiber loads afterchemical precipitate formation. Various features and advantages of thepresent invention will be described in more detail below.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided an increasedefficiency strainer system which is particularly suited for use in theemergency core cooling system of a nuclear power plant. In certainembodiments of the present invention, the strainer system includes oneor more strainer cassettes or cartridges, with each such cassette orcartridge including a plurality of strainer pockets disposed inside-by-side relation to each other. Multiple cassettes or cartridgesmay be assembled together to form a strainer module of the strainersystem.

More particularly, in one embodiment of the present invention, eachcartridge has a generally quadrangular configuration, as do theindividual strainer pockets included therein. In this particularembodiment, the strainer pockets of the cartridge each define an inflowend, with the inflow ends of the strainer pockets of the cartridgefacing in a common direction. Within the cartridge, or the moduleincluding multiple cartridges, the inflow ends of one or more of thestrainer pockets may be enclosed by an elastic metal membrane. When in aclosed position, the membrane prevents liquid flow into thecorresponding strainer pocket via the inflow end thereof. The membraneremains closed when only a low pressure load is exerted thereon, but isdeflected or deformed into an open position when a high pressure load isexerted thereon. The movement of the membrane to its open positioneffectively opens the corresponding strainer pocket, thus allowing forthe flow of liquid into the interior of the strainer pocket via theinflow end thereof.

In accordance with another aspect of the present invention, it iscontemplated that the above-described strainer cartridge(s) included ina strainer module of the strainer system may include flat,non-perforated face plates which extend from a surface of thecartridge(s) adjacent the inflow ends of the strainer pockets thereof.The non-perforated extended face plates cause the edges of a fiber andparticulate debris bed forming at the inflow ends of the strainerpockets to compress and slowly curl in from an originally flushrelationship to the face plates, which results in the creation of smallflow paths between the face plates and debris bed as differentialpressure continues to rise, thus allowing flow into the strainer andreducing head loss. As the strainer area affected by the flow receivesmore debris, fiber, particulate and chemical precipitate, the head lossincreases until another flow path is opened into another area of thestrainer. The creation of the flow paths, as caused by the optionalinclusion of the extended face plates with the strainer cartridge(s),effectively reduces the maximum differential pressure experienced acrossthe strainer and provides a way to potentially reduce required strainersurface area necessary to satisfy a particular containment recirculationnet positive suction head requirement.

In accordance with another embodiment of the present invention, thestrainer cassette or cartridge has a generally circular configuration,with the strainer pockets thereof being arranged in side-by-siderelation to each other in a generally circular pattern. In thisparticular embodiment, one or more of the strainer pockets of thestrainer cartridge may be outfitted with the aforementioned elasticmetal membrane. Additionally, if a strainer module is constructedincluding multiple circularly configured strainer cartridges disposed instacked relation to each other, it is contemplated that all of thestrainer pockets of one or more of the strainer cartridges included inthe module may be outfitted with an elastic metal membrane.

In accordance with another embodiment of the present invention, thestrainer system comprises a plurality of cylindrically configured,tubular primary strainer elements. Each of the primary strainer elementsdefines an inflow end, and comprises concentrically positioned inner andouter walls which are each fabricated from a perforated metal material.The inflow end is typically defined solely by the inner wall of theprimary strainer element. The inflow end of one or more of the primarystrainer elements included in the strainer system may be covered by arupture disc or segmented membrane which mirrors the functionality ofthe above-described elastic metal membrane. In this regard, the rupturedisc or segmented membrane covering the inflow end of one or more of theprimary strainer elements is operative to move from a normally closedposition to an open position allowing direct liquid flow into theinterior of the inner wall of the primary strainer element via theinflow end defined thereby when such rupture disc or segmented membraneis subjected to a high pressure load.

In this particular embodiment of the strainer system, it is alsocontemplated that one or more of the primary strainer elements mayinclude a secondary strainer element concentrically positioned withinthe inner wall of the primary strainer element, thus creating a doublecylinder strainer construction as opposed to the single cylinderstrainer construction provided by a primary strainer element standingalone. The secondary strainer element, if included with a primarystrainer element, has a construction mirroring that of the surroundingprimary strainer element, with the inflow end defined by the inner wallof the secondary strainer element optionally being covered by theabove-described rupture disc or segmented membrane. In the doublecylinder strainer construction, no rupture disc or segmented membrane isprovided on the inflow end defined by the inner wall of the primarystrainer element due to the concentric positioning of the secondarystrainer element therein.

The present invention is best understood by reference to the followingdetailed description when read in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

These, as well as other features of the present invention, will becomemore apparent upon reference to the drawings wherein:

FIG. 1 is a front perspective view of a prior art strainer cassette orcartridge;

FIG. 2 is a rear perspective view of the prior art strainer cartridgeshown in FIG. 1;

FIG. 3 is a front perspective view of a strainer module includingmultiple strainer cartridges constructed in accordance with a firstembodiment of the present invention;

FIG. 4 is a cross-sectional view of an exemplary strainer systemincluding an opposed pair of the strainer modules shown in FIG. 3;

FIG. 5 is an enlargement of the encircled region 5 shown in FIG. 4;

FIG. 6 is a perspective view of a strainer module constructed inaccordance with a second embodiment of the present invention;

FIG. 7 is a cross-sectional view taken along line 7-7 of FIG. 6;

FIG. 8 is an enlargement of encircled region 8 shown in FIG. 7;

FIG. 9 is a perspective view of a strainer module constructed inaccordance with a third embodiment of the present invention;

FIG. 10 is a perspective view of a strainer module constructed inaccordance with a fourth embodiment of the present invention; and

FIG. 11 is an enlargement of the encircled region 11 shown in FIG. 10.

Common reference numerals throughout the drawings and detaileddescription to indicate like elements.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein the showings are for purposes ofillustrating preferred embodiments of the present invention only, andnot for purposes of limiting the same, FIGS. 1 and 2 illustrate anexisting, prior art strainer cassette or cartridge 10. The cartridge 10has a generally quadrangular configuration. When viewed from theperspective shown in FIGS. 1 and 2, the cartridge 10 includes an opposedpair of side walls 12 extending in spaced, generally parallel relationto each other, a top wall 14 extending between the top edges of the sidewalls 12, a bottom wall 16 extending in spaced, generally parallelrelation to the top wall 14 between the bottom edges of the side walls12, and a back wall 18 which extends between the back edges of the sidewalls 12 and between the back edges of the top and bottom walls 14, 16.In the strainer cartridge 10, the side, top, bottom and back walls 12,14, 16, 18 are each fabricated from a perforated metal material.

The strainer cartridge 10 further comprises a plurality of separatorplates 20 which, when viewed from the perspective shown in FIGS. 1 and2, are horizontally and vertically oriented between the side, top,bottom and back walls 12, 14, 16, 18 in a prescribed arrangement. Moreparticularly, the separator plates 20 are arranged such that they, alongwith the side, top, bottom and back walls 12, 14, 16, 18, collectivelydefine a plurality of strainer pockets 22 within the strainer cartridge10. In the exemplary strainer cartridge 10 shown in FIGS. 1 and 2, atotal of eight (8) strainer pockets 22 are included in the strainercartridge 10, with the strainer pockets 22 being arranged in twoside-by-side vertical columns of four (4) strainer pockets 22 each. Likethe side, top, bottom and back walls 12, 14, 16, 18, each of theseparator plates 20 is fabricated from a perforated metal material.

As is most apparent from FIGS. 4 and 5, the horizontally orientedseparator plates 20 included in the strainer cartridge 10 are preferablyformed in a manner which imparts a generally parabolic configuration toeach of the strainer pockets 22. In this regard, each of the strainerpockets 22 includes an open inflow end 24 at the front edges of theside, top, bottom and back walls 12, 14, 16, 18 and the front edges ofthe separator plates 20. In addition to the inflow end 24, each strainerpocket 22 includes an arcuate, concave back end 26 which is disposedproximate the back wall 18 of the strainer cartridge 10.

As will be discussed in more detail below, in accordance with thepresent invention, the strainer cartridge 10 is provided with additionalstructural features which enhance the functionality thereof, and hencethe functionality of a strainer module assembled to include one or moreenhanced strainer cartridges. FIG. 3 depicts an exemplary strainermodule 28 assembled by placing multiple strainer cartridges inside-by-side relation to each other. In the exemplary strainer module 28shown in FIG. 3, a total of seven (7) strainer cartridges are includedtherein, with three (3) of the strainer cartridges being “enhanced.” Forpurposes of clarity, the “enhanced” strainer cartridges constructed inaccordance with the present invention are labeled with the referencenumber “10 a” in FIGS. 3 and 4 to differentiate the same from the priorart strainer cartridges 10. The remaining four (4) strainer cartridgesincluded in the strainer module 28 are the prior art, non-enhancedstrainer cartridges 10 described above. Those of ordinary skill in theart will recognize that the strainer module 28 may be assembled toinclude one or more enhanced strainer cartridges 10 a and one or morestandard strainer cartridges 10 in any combination, the aforementionedarrangement of three strainer cartridges 10 a and four strainercartridges 10 being exemplary only.

When assembled to form the strainer module 28 shown in FIG. 3, thestrainer cartridges 10, 10 a are arranged such that the inflow ends 24defined by the strainer pockets 22 thereof face in a common direction.When the strainer module 28 is integrated into a strainer system, asuction plenum is defined between the back wall of the strainer module28 collectively defined by the back walls 18 of the strainer cartridges10, 10 a thereof. The suction plenum is fluidly coupled to a pump which,when activated, creates suction in the suction plenum as results in adifferential pressure condition which causes liquid to be drawn into theinflow ends 24 of the strainer pockets 22 of the strainer cartridges 10,10 a, and thereafter through the strainer pockets 22 of the strainercartridges 10, 10 a into the suction plenum. As will be recognized, flowthrough the strainer cartridges 10, 10 a of the strainer module 28 isachieved as a result of the fabrication of the strainer cartridges 10,10 a from the perforated metal material described above.

FIG. 4 depicts an exemplary strainer system 30 which includes thestrainer module 28 shown in FIG. 3 as paired with a second strainermodule 29. The strainer module 29 is virtually identical to the strainermodule 28, with the sole distinction being that is assembled with onlythe standard strainer cartridges 10 (i.e., a total of seven (7) of thecartridges 10 in side-by-side relation to each other). In the exemplarystrainer system 30, the strainer modules 28, 29 are oriented in spaced,back-to-back relation to each other, with a suction plenum 32 beingdefined between the back walls of the strainer modules 28, 29. As willbe recognized, in the exemplary strainer system 30, the activation of apump fluidly coupled to the suction plenum 32 effectively draws liquidinto the inflow ends 24 of the strainer pockets 22 of the strainercartridges 10, 10 a within each of the opposed strainer modules 28, 29,such liquid ultimately passing through the strainer cartridges 10, 10 aand into the suction plenum 32. Again, the configuration of the strainermodule 28 shown in FIG. 3 and the configuration of the strainer system30 shown in FIG. 4 are intended to be exemplary only, with the presentinvention being directed in large measure toward the structural featuresadded to the strainer cartridge 10 which facilitate the creation of theenhanced strainer cartridge 10 a. These structural features orenhancements will now be described with particular regard to FIGS. 4 and5.

Referring now to FIGS. 4 and 5, in accordance with the presentinvention, it is contemplated that one or more of the strainer pockets22 of each of the strainer cartridges 10 a included in the exemplarystrainer module 28 may be outfitted with a membrane 34 which isselectively moveable between a closed position and an open position. Inthe exemplary strainer system 30 shown in FIG. 4, a prescribed number ofthe strainer pockets 22 of the strainer module 28 included in thestrainer system 30 are each outfitted with a membrane 34. Each membrane34 is preferably fabricated from an elastic metal material and ispivotally connected to a corresponding strainer pocket 32 at a joint 36.Each membrane 34 is positioned at the inflow end 24 of the correspondingstrainer pocket 22, and is sized so as to substantially cover suchinflow end 24. Additionally, as is seen in FIG. 5, each strainer pocket22 outfitted with a membrane 34 further preferably includes a membranestopper 38 mounted thereto in opposed relation to the joint 36. In thisregard, that edge of the membrane 34 disposed furthest from the joint 36is normally abutted against the corresponding membrane stopper 38 whenthe membrane 34 is in its closed position.

As indicated above, within one or more of the strainer cartridges 10 aof the strainer module 28, the inflow end(s) 24 of one or more of thestrainer pockets 22 may be enclosed by an elastic metal membrane 34.When in the closed position shown in FIGS. 4 and 5, the membrane 34substantially prevents liquid flow into the corresponding strainerpocket 22 via the inflow end 24 thereof. The membrane 34 is normallymaintained in its closed position by the abutment of one edge thereofagainst the corresponding membrane stopper 38, and remains in suchclosed position when only a low pressure load is exerted thereon.However, the exertion of a high pressure load on the membrane 34effectively facilitates the deflection of deformation thereof into theopen position in the manner shown by the phantom lines included in FIG.5. As is apparent from FIG. 5, the level of flexion or deformation ofthe membrane 34 must be sufficient to cause the same to move beyond andthus be effectively disengaged from corresponding membrane stopper 38.Once the membrane 34 disengages the corresponding membrane stopper 38,such membrane 34 is free to rotate or pivot about the joint 36 to itsfully open position. The movement of the membrane 34 to its openposition effectively opens the corresponding strainer pocket 22, thusallowing for the flow of liquid into the interior of such strainerpocket 22 via the now unobstructed inflow end 24 thereof. Those strainerpockets 22 outfitted with the membranes 34 may be referred to aspressure controlled pockets or PCP's.

Within the exemplary strainer module 28 including the strainercartridges 10 a, it is contemplated that approximately five percent (5%)of the strainer pockets 22 included in the strainer cartridges 10 a willeach be outfitted with a membrane 34 and thus function as a PCP. As aresult, approximately ninety-five percent (95%) of the strainer pockets22 included in the strainer cartridges 10 a of the strainer module 28will be open without membranes 34. With regard to the distribution ofthose strainer pockets 22 including membranes 34, it is alsocontemplated that such PCP's should be kept “clean” during the phase ofdebris coming on the strainer module 28 in the case of an accident.Accordingly, it is desirable that the strainer pockets 22 outfitted withmembranes 34 be installed or located in a dead water zone of thestrainer module 28 within the overall strainer system. Typically, thisdead water zone may be in the middle of the strainer module 28 and/or atthe opposite location of where debris typically enters into thecontainment. When the strainer module 28 is in use upon the occurrenceof an accident, it is contemplated that the strainer pockets 22outfitted with the membranes 34 will not open simultaneously, but ratherwill open sequentially as needed to cope with chemical effects in thedebris laden water circulating through the strainer module 28. Thesequential opening of the PCP's, as will usually occur when the pressureload exerted thereagainst by the debris field forming on the strainermodule 28 exceeds the above-described high pressure threshold,facilitates an effective, controlled reduction in head loss, and furtheravoids any head loss “jump” due to clogging.

As is further shown in FIGS. 3 and 4, the functional advantages to theexemplary strainer module 28 as a result of the inclusion of one or morePCP's in each of the strainer cartridges 10 a may be further enhanced byadditionally outfitting the strainer module 28 with flat, non-perforatedface plates 40 which extend from prescribed surfaces of the strainermodule 28 adjacent the inflow ends 24 of the strainer pockets 22 definedby the strainer cartridges 10, 10 a thereof. More particularly, as isbest seen in FIG. 3, the exemplary strainer module 28 includes amultiplicity of the extended face plates 40 which are attached to thefront edges of corresponding ones of the top and bottom walls 14, 16 andseparator plates 20 of the strainer cartridges 10, 10 a included in thestrainer module 28. The face plates 40 are arranged so as to define twogenerally quadrangular (e.g., rectangular) frames. As is seen in FIG. 3,the two quadrangular frames defined by the face plates 40 extend inspaced, generally parallel relation to each other. Since the face plates40 are attached to the front edges of the top and bottom walls 14, 16and separator plates 20, the frames defined thereby effectivelycircumvent the inflow ends 24 of a prescribed number of the strainerpockets 22, one or more of which may be outfitted with a membrane 34 soas to function as an above-described PCP. Those of ordinary skill in theart will recognize that the particular arrangement of the face plates 40as shown in FIG. 3 is exemplary only, and that the number, size andarrangement of the face plates 40 may be selectively varied as needed toprovide the functionality enhancements described below based on theparticular environment or configuration of the strainer system in whichthe strainer module 28 outfitted with the face plates 40 is to beintegrated.

As indicated above, the face plates 40 extend forwardly from thestrainer module 28 such that the two quadrangular frames defined by theface plates 40 effectively circumvent the inflow ends 24 of a prescribednumber of the strainer pockets 22. As shown in FIG. 4, in the exemplarystrainer system 30, though the strainer module 29 is not assembled toinclude the enhanced strainer cartridges 10 a, such strainer module 29is still outfitted with the above-described face plates 40 which arearranged on the strainer module 29 in the same pattern described abovein relation to the strainer module 28. In this regard, the functionaladvantages attributable to the inclusion of the face plates 40 on thestrainer module 28 are equally applicable to the strainer module 29,despite the absence therein of any of the PCP's. When included with thestrainer module 29, the face plates 40 protrude forwardly from thestrainer module 29 such that the spaced, generally parallel pair ofquadrangular frames defined thereby circumvent the inflow ends 24 of aprescribed number of the strainer pockets 22 of the strainer module 29.

As is further apparent from FIG. 4, the face plates 40 included with thestrainer modules 28, 29 cause the edges of a fiber and particulatedebris bed 42 which may form at the inflow ends of the strainer pockets22 to compress and slowly curl in from an originally flush relationshipto the inner surfaces of the face plates 40. This curling in of thedebris bed 42 results in the creation of small flow paths between theinner surfaces of the face plates 40 and the debris bed 42 asdifferential pressure continues to rise, thus promoting liquid flowthrough the strainer modules 28, 29 and reducing head loss. The creationof these flow paths, as caused by the inclusion of the face plates 40with the strainer modules 28, 29, effectively reduces the maximumdifferential pressure experienced across the strainer modules 28, 29.Those of ordinary skill in the art will recognize that the face plates40 may be included on one, both or neither of the face plates 40. Inthis regard, the inclusion of the face plates 40 with one or both of thestrainer modules 28, 29 is purely optional.

Referring now to FIGS. 6-8, there is shown a strainer module 100constructed in accordance with a second embodiment of the presentinvention. The strainer module 100 comprises a generally cylindrical,tubular main body section 102 which defines a section plenum 104extending axially therethrough. Extending radially from the outersurface of the main body section 102 in spaced, generally parallelrelation to each other are a plurality of circularly configuredseparator plates 106. Though not shown in FIG. 6, the main body section102 includes openings formed therein which allow liquid flowing betweenthe separator plates 106 to be drawn into the suction plenum 104 viasuch openings upon the creation of a pressure differential conditionattributable to the activation of a pump fluidly coupled to the suctionplenum 104.

The strainer module 100 further comprises at least one circularlyconfigured strainer cartridge 108 which is positioned between aprescribed adjacent pair of the separator plates 106. The strainercartridge 108 comprises a multiplicity of wall members 110 which arearranged and attached to each other so as to collectively define aplurality of strainer pockets 112 of the strainer cartridge 108. In thestrainer cartridge 108 shown in FIGS. 6 and 7, a total of ten (10)strainer pockets 112 are included in the strainer cartridge 108, withthe strainer pockets 112 being arranged in a circularly configuredarray. The wall members 110 of the strainer cartridge 108 are eachpreferably fabricated from a perforated metal material.

In the strainer cartridge 108 included in the strainer module 100, eachof the strainer pockets 112 includes an open inflow end 114 which isdefined by the peripheral edges of corresponding wall members 110. Thus,as seen in FIGS. 6 and 7, the inflow ends 114 of the strainer pockets112 are directed or face radially outwardly relative to the suctionplenum 104 defined by the main body section 102. In the strainercartridge 108, each of the strainer pockets 112 is preferably outfittedwith a membrane 116 which mimics the functionality of theabove-described membrane 34. In this regard, each membrane 116 ispreferably fabricated from an elastic metal material and is pivotallyconnected to a corresponding strainer pocket 112 at a joint 118. Eachmembrane 116 is positioned at the inflow end 114 of the correspondingstrainer pocket 112, and is sized so as to substantially cover suchinflow end 114. As is best seen in FIG. 7, each strainer pocket 112 isfurther outfitted with a membrane stopper 120 which is mounted theretoin opposed relation to the joint 118. In this regard, that edge of themembrane 116 disposed furthest from the joint 118 is normally abuttedagainst the corresponding membrane stopper 120 when the membrane 116 isin its closed position.

In the strainer cartridge 108, each membrane 116, when in its closedposition, substantially prevents liquid flow into the correspondingstrainer pocket 112 via the inflow end 114 thereof. Each membrane 116 isnormally maintained in its closed position by the abutment of one edgethereof against the corresponding membrane stopper 120, and remains insuch closed position when only a low pressure load is exerted thereon.However, the exertion of a high pressure load on the membrane 116effectively facilitates the flexion or deformation thereof into the openposition in the manner shown by the phantom lines included in FIG. 8. Asis apparent from FIG. 8, the level of flexion or deformation of themembrane 116 must be sufficient to cause the same to move beyond andthus be effectively disengaged from the corresponding membrane stopper120. Once the membrane 116 disengages the corresponding membrane stopper120, such membrane 116 is free to rotate or pivot about the joint 118 toits fully open position. The movement of the membrane 116 to its openposition effectively opens the corresponding strainer pocket 112, thusallowing for the flow of liquid into the interior of such strainerpocket 112 via the now unobstructed inflow end 114 thereof.

Though, in FIG. 7, each of the strainer pockets 112 included in thestrainer cartridge 108 is shown as being outfitted with a membrane 116,those of ordinary skill in the art will recognize that any number of thestrainer pockets 112 less than the entire number thereof may beoutfitted with a membrane 116 in any distribution or arrangement.Further, the strainer cartridge 108 may be assembled to include greateror fewer than ten strainer pockets 112 without departing from the spiritand scope of the present invention. Additionally, though the strainermodule 100 is shown as including only one strainer cartridge 108 betweenone adjacent pair of the separator plates 106, those of ordinary skillin the art will also recognize that one or more additional strainercartridges 108 may be included in the strainer module 100 between one ormore other adjacent pairs of the separator plates 106. Within thestrainer cartridge 108, it is contemplated that the strainer pockets 112outfitted with the membranes 116 will not open simultaneously, butrather will open sequentially as needed to cope with chemical effects indebris laden water circulating through the strainer module 100. Thesequential opening of the membranes 116 will usually occur when thepressure load exerted thereagainst by the debris field forming on thestrainer module 100 exceeds a prescribed high pressure threshold asdescribed above in relation to the strainer module 28.

Referring now to FIG. 9, there is shown a strainer module 200constructed in accordance with a third embodiment of the presentinvention. The sole distinction between the strainer modules 100, 200lies in the separator plates 206 included in the strainer module 200each having a generally quadrangular (e.g. square) configuration, asopposed to the circular configuration of the above-described separatorplates 106 included in the strainer module 100.

Referring now to FIGS. 10 and 11, there is shown a strainer module 300constructed in accordance with a fourth embodiment of the presentinvention. The strainer module 400 comprises a main body section 402which has a generally quadrangular cross-sectional configuration anddefines a suction plenum 404. Attached to a common wall of the main bodysection 402 and protruding therefrom in spaced, generally parallelrelation to each other are a plurality of (e.g., four) cylindricallyconfigured, tubular primary strainer elements 406 which each fluidlycommunicate with the suction plenum 404. Each of the primary strainerelements 406 defines an inflow end 408, and comprises concentricallypositioned outer and inner walls 410, 412. The outer and inner walls410, 412 are each fabricated from a perforated metal, mesh-likematerial. The inflow end 408 is typically defined solely by the innerwall 412 of the primary strainer element 406.

In the exemplary strainer module 400, the inflow end 408 of one of theprimary strainer elements 406 is covered by a rupture disk or segmentedmembrane 414 which mirrors the functionality of the above-describedmembranes 34, 116. In this regard, the segmented membrane 414 isoperative to move from a normally closed position (as shown in FIGS. 10and 11) to an open position allowing direct liquid flow into theinterior of the inner wall 412 of the corresponding primary strainerelement 406 via the inflow end 408 defined thereby when such segmentedmembrane 414 is subjected to a high pressure load beyond a prescribedthreshold. The segmented membrane 414 has a generally circularconfiguration and defines four (4) membrane quadrants which areindividually movable relative to each other.

In the strainer module 400 shown in FIGS. 10 and 11, it is alsocontemplated that one or more of the primary strainer elements 406 mayinclude a secondary strainer element 416 concentrically positionedwithin the inner wall 412 of the primary strainer element 406, thuscreating a double cylinder strainer construction as opposed to thesingle cylinder strainer construction provided by any primary strainerelement 406 standing alone. The secondary strainer elements 416 definesan inflow end 418, and comprises concentrically positioned outer andinner walls 420, 422. The outer and inner walls 420, 422 are eachfabricated from a perforated metal, mesh-like material. The inflow end418 is typically defined solely by the inner wall 420 of the secondarystrainer element 416.

In the secondary strainer module 416, the inflow end 418 is covered by arupture disk or segmented membrane 424 which mirrors the functionalityof the above-described segmented membrane 414. In this regard, thesegmented membrane 424 is operative to move from a normally closedposition (as shown in FIGS. 10 and 11) to an open position allowingdirect liquid flow into the interior of the inner wall 422 of thesecondary strainer element 416 via the inflow end 418 defined therebywhen such segmented membrane 424 is subjected to a high pressure loadbeyond a prescribed threshold. The segmented membrane 424 also has agenerally circular configuration and defines four (4) membrane quadrantswhich are individually movable relative to each other.

When the exemplary strainer module 400 is integrated into a strainersystem, the creation of a pressure differential condition attributableto the activation of a pump fluidly coupled to the suction plenum 404causes liquid to be drawn through the primary strainer elements 406 andthe sole secondary strainer element 416 into the suction plenum 404.Within the strainer module 400, it is contemplated that the segmentedmembranes 414, 424 will not open simultaneously, but rather will opensequentially as needed to cope with chemical effects in debris ladenwater circulating through the strainer module 400. As described above inrelation to the strainer module 28, the sequential opening of thesegmented membranes 414, 424 will usually occur when the pressure loadexerted thereagainst by a debris field forming of the strainer module400 exceeds a prescribed high pressure threshold.

Those of ordinary skill in the art will recognize that greater or fewerthan four primary strainer elements 406 may be included in the strainermodule 400 without departing from the spirit and scope of the presentinvention. Along these lines, more than one primary strainer element 406may be outfitted with a segmented membrane 414, or with theabove-described secondary strainer element 416 including its ownsegmented membrane 424. Further, no primary strainer module 406 neednecessarily be outfitted with a secondary strainer element 416.

This disclosure provides exemplary embodiments of the present invention.The scope of the present invention is not limited by these exemplaryembodiments. Numerous variations, whether explicitly provided for by thespecification or implied by the specification, such as variations instructure, dimension, type of material and manufacturing process may beimplemented by one of skill in the art in view of this disclosure.

What is claimed is:
 1. A strainer module, comprising: at least onestrainer cartridge defining a plurality of pressure activated strainerpockets and a plurality of open strainer pockets separate from theplurality of pressure activated strainer pockets, the plurality ofpressure activated strainer pockets and each of the open strainerpockets defining an open inflow end; and a plurality of deformablemembranes attached to the at least one strainer cartridge in a closedposition substantially covering the inflow ends of respective ones ofthe plurality of pressure activated strainer pockets; each deformablemembrane being deformably transitionable from the closed position tosubstantially prevent fluid flow into the pressure activated strainerpocket through the inflow end thereof, to an open position wherein theinflow end of the corresponding pressure activated strainer pocket is atleast partially unobstructed allowing for fluid flow into the inflow endof the pressure activated strainer pocket and through a strainer surfaceat least partially defining the pressure activated strainer pocket; eachdeformable membrane being fabricated from an elastic material adapted toflex upon the application of a prescribed pressure load thereto, and themovement of the membrane from the closed position to the open positionis facilitated by the flexion thereof.
 2. The strainer module of claim 1wherein the membrane is fabricated from a non-perforated elastic metalmaterial.
 3. The strainer module of claim 1 further comprising: at leastone membrane stopper attached to the at least one strainer cartridgeadjacent the inflow end of the respective pressure activated strainerpocket substantially covered by the membrane; the membrane stopper beingsized and configured to normally maintain the membrane in the closedposition, and to permit the membrane to flex to the open position uponthe application of the prescribed pressure load thereto.
 4. The strainermodule of claim 3 wherein the membrane is pivotally connected to the atleast one strainer cartridge at a joint which is disposed adjacent theinflow end of the respective pressure activated strainer pocket inopposed relation to the membrane stopper.
 5. The strainer module ofclaim 1 wherein the plurality of membranes are arranged on the strainercartridge in a prescribed pattern.
 6. The strainer module of claim 1wherein the pressure activated strainer pockets and the plurality ofopen strainer pockets are arranged in at least two side-by-side columnswhich extend in generally parallel relation to each other such that theinflow ends of the strainer pockets face in a common direction.
 7. Thestrainer module of claim 1 further comprising a plurality of face platesattached to the at least one strainer cartridge in a manner wherein thefaceplates collectively define a frame which extends forwardly relativeto and at least partially circumvents the inflow ends of at least someof the strainer pockets.
 8. A strainer module, comprising: at least onestrainer cartridge defining a plurality of pressure activated strainerpockets and a plurality of open strainer pockets separate from theplurality of pressure activated strainer pockets, the plurality ofpressure activated strainer pockets and each of the open strainerpockets defining an open inflow end; and a plurality of deformablemembranes attached to the at least one strainer cartridge in a closedposition substantially covering the inflow ends of respective ones ofthe plurality of pressure activated strainer pockets; each of thedeformable membranes being individually and deformably transitionablefrom the closed position to substantially prevent fluid flow into thepressure activated strainer pocket through the inflow end thereof, andan open position wherein the inflow end of the corresponding pressureactivated strainer pocket is at least partially unobstructed allowingfor fluid flow into the inflow end of the pressure activated strainerpocket and through a strainer surface at least partially defining thepressure activated strainer pocket.
 9. The strainer module of claim 8wherein each of the membranes is fabricated from an elastic,non-perforated metal material adapted to flex upon the application of aprescribed pressure load thereto, and the movement of each of themembranes from the closed position to the open position is facilitatedby the flexion thereof.
 10. The strainer module of claim 8 wherein thepressure activated strainer pockets comprise approximately five percentof the combined totality of the pressure activated strainer pockets andopen strainer pockets included in the at least one strainer cartridge.11. The strainer module of claim 8 further comprising: a plurality ofmembrane stoppers attached to the at least one strainer cartridgeadjacent the inflow ends of respective ones of the strainer pocketswhich are substantially covered by respective ones of the membranes;each of the membrane stoppers being sized and configured to normallymaintain a respective one of the membranes in the closed position, andto permit a respective one of the membranes to flex to the open positionupon the application of the prescribed pressure load thereto.
 12. Thestrainer module of claim 11 wherein each of the membranes is pivotallyconnected to the at least one strainer cartridge at a joint which isdisposed adjacent the inflow end of a respective one of the strainerpockets in opposed relation to a respective one of the membranestoppers.
 13. The strainer module of claim 8 wherein the strainerpockets are arranged in a plurality of side-by-side columns which extendin generally parallel relation to each other such that the inflow endsof the strainer pockets face in a common direction.
 14. The strainermodule of claim 8 further comprising a plurality of face plates attachedto the at least one strainer cartridge in a manner wherein thefaceplates collectively define a frame which extends forwardly relativeto and at least partially circumvents the inflow ends of at least someof the strainer pockets.
 15. A strainer cartridge, comprising: aplurality of pressure activated strainer elements and an open strainerelement, each of which includes an inflow end; and a plurality ofdeformable membranes attached to respective ones of the pressureactivated strainer elements in a closed position covering the inflow endthereof, the deformable membrane being positioned such that flow intothe inflow end of the open strainer element is unobstructed by thedeformable membrane; each deformable membrane being selectively anddeformably transitionable from the closed position to substantiallyprevent fluid flow into the corresponding pressure activated strainerelement through the inflow end thereof, and an open position wherein theinflow end is at least partially unobstructed allowing for fluid flowinto the corresponding pressure activated strainer element through theinflow end thereof.
 16. The strainer cartridge of claim 15 wherein: eachof the pressure activated strainer elements has a cylindricallyconfigured, tubular configuration; and each membrane has a generallycircular, segmented configuration defining four membrane quadrants whichare individually moveable relative to each other.
 17. A strainer module,comprising: at least one strainer cartridge defining a plurality offluid inflow portions including a plurality of pressure activated inflowportions and an open inflow portion; a plurality of membranes attachedto the at least one strainer cartridge in a closed position, whereineach membrane covers a respective one of the plurality of fluid inflowportions; the strainer cartridge being configured such that eachpressure activated inflow portion is transitionable relative to the openinflow portion from a closed state wherein the corresponding membrane isin the closed position thereby substantially preventing fluid flow intothe pressure activated inflow portion, to an open state wherein thepressure activated inflow portion is at least partially unobstructed toallow for the flow of a fluid therein and through a strainer surface atleast partially defining the pressure activated inflow portion.
 18. Thestrainer cartridge of claim 15 wherein the strainer cartridge comprisesa plurality of strainer elements which are arranged in a generallycircular array such that the inflow ends thereof are directed radiallyoutward relative to a common axis.
 19. The strainer cartridge of claim18 wherein a plurality of membranes is attached to the strainercartridge in a manner substantially covering the inflow ends ofrespective ones of the strainer elements.